TCP And UDP Over IPX Networks With Fixed Path MTU (RFC1791)
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2019-Feb-12
Internet Society Requests For Comment (RFCs)
TCP/IPX allows TCP/IP applications to run over IPX networks by letting TCP and UDP run over IPX. And this memo specifies the packet format and operational procedures for running TCP and UDP over IPX. This document defines an Experimental Protocol for the Internet community. This does not specify an Internet standard of any kind.
Network Working Group T. Sung Request for Comments: 1791 Novell, Inc. Category: Experimental April 1995
TCP And UDP Over IPX Networks With Fixed Path MTU
Status of this Memo
This document defines an Experimental Protocol for the Internet community. This does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited.
Internet Engineering Steering Group comment from the Area Director for Transport Services: Please note well that this memo is an individual product of the author. Implementation experience, particularly on the effectiveness of the protocols in dual-stack environments, is needed.
Most of network applications run on some sort of transports. And, if one is to let such applications to run over a foreign network protocol, the simplest way would be to allow the applications’ transports to run over that network protocol. For TCP/IP applications, that transport is TCP or UDP. Hence, to let TCP/IP applications run over IPX, we would need to have TCP and UDP run over IPX. And, once TCP and UDP are allowed to run over IPX, all TCP and UDP based applications, such as HTTP for WWW, or NFS, can easily be made to work over IPX networks.
DLsw is another example of such applications. As it is a TCP application (and TCP requires IP), the administrator is forced to run IP on his network in order to support DLsw. If the site was an IPX shop, it means that he now must manage IP protocol/addresses in addition to IPX. If TCP could be made to run on IPX, then he would not have to add IP to his repertoire of network protocols to manage.
TCP/IPX allows TCP/IP applications to run over IPX networks by letting TCP and UDP run over IPX. And this memo specifies the packet format and operational procedures for running TCP and UDP over IPX.
Sung [Page 1]
RFC 1791 TCP And UDP Over IPX April 1995
2. Running UDP Over IPX
Since UDP datagrams can be up to 64K octets long, and the size of IPX packet is limited to that of the path MTU, large UDP datagrams must be fragmented. And, since IPX does not support fragmentation, large UDP datagrams must be fragmented before they are passed to IPX. For that purpose, a new protocol called IPXF (IPX Fragmentation layer), is invented. UDP must run on IPXF rather than directly on IPX. IPXF layer is described in section 4.
To IPXF service users, IPXF behaves just like IPX except that IPXF accepts datagram larger than the IPX path MTU. As such, we describe UDP in this section as if it is running on IPX.
UDP must send and receive the packets on IPX/IPXF socket 0x9092. Though it may be possible to send a packet from sockets other than 0x9092, such sockets cannot receive UDP datagram destined to a well known socket 0x9092. Hence, the bidirectional communcation may not be established if a socket other than 0x9092 is used to send UDP datagram. For that reason. UDP/IPX does not allow source sockets other than 0x9092. If a datagram...